Princess Diana's biographer praises Elizabeth Debicki's 'authentic' portrayal in 'The Crown': 'It was like being with a ghost'

• Spoilers ahead for season five, episode two, of "The Crown."
• The author of Princess Diana's 1992 biography said Elizabeth Debicki's performance is "unnerving."

Elizabeth Debicki's portrayal of Princess Diana in "The Crown" season five is "unnerving," said the author of the late royal's biography.

Andrew Morton, who wrote the book "Diana: Her True Story" in 1992, told The Daily Beast that he was "blown away" by Debicki's performance in the Netflix hit series.

"I was blown away by how authentic Elizabeth Debicki was in her portrayal of Diana," the biographer said. "It was like being back in the room with her 30 years ago. It was unnerving. It was like being with a ghost. It spoke to me very clearly."

Diana, died in 1997, five years after the biography was published.

In the second episode of the new season, the series dramatizes how Morton's biography came about. Morton (who is played by Andrew Steele) approaches a friend of Diana, James Colthurst (played by Oliver Chris), who acts as a go-between between the princess and the journalist.

Morton gives Diana a chance to tell her story by getting her to record her answers on tape so they never have to meet. She also provides friends for him to interview so she can claim plausible deniability.

Morton told The Daily Beast: "Writing that book was the royal equivalent of 'All The President's Men.' You would see danger in the shadows. From the first moment that I heard the tapes, I was very careful. I remember standing back from the edge of the platform on the subway going home."

He continued: "I had been admitted into a secret circle. The secret circle knew the truth about Diana's life, and many powerful people did not want that truth to be revealed."

However, in the episode, it seems that the news of the biography gets out and there is a campaign to intimidate both Morton and Colthurst. Morton's office is ransacked and Colthurst is run off the road by a van.

Morton said that both of these incidents actually happened.

"My office was broken into," he said. "It happened just a few days after I had been warned, separately, by [journalists] Arthur Edwards and Richard Kay, that the security forces were looking carefully to find my source."

He added: "And James was knocked off his bike in Parliament Square — and left scrambling in the gutter to pick up a tape recording of Diana."

Morton also said that Diana's room was "swept for bugs," like in the episode.

"'The Crown' shows the sense of unnamed and anonymous watchers and it's absolutely true, there is no need for Peter Morgan to make anything up," he added.

The fifth season has received backlash regarding historical inaccuracies. Former prime ministers Sir John Major and Sir Tony Blair have criticized the series for displaying scenes in which the then-Prince Charles has secret meetings with them during the 1990s to ask them to put him on the throne.

In a letter to The Telegraph last week, Major wrote that the scene would be "profoundly hurtful to a family who are still grieving for the very person on whose life the entire drama was founded."

"The Crown" season five is available now on Netflix.